Eaton Cutler-Hammer ATC-300 User manual

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O & M Manual for ATC-300 2-Position
Contactor Based Transfer Switch
Instruction Booklet
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Description Page
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Receiving, Handling, and Storage . . . . . . . . . . . . . . . . . . . 6
Equipment Description . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Installation and Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
Testing and Problem Solving . . . . . . . . . . . . . . . . . . . . . . .21
Adjustments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
Renewal Parts Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
ATC-300 Contactor Based ATS Quick Start Instructions . . .25
Appendix A: Pickup / Dropout Tables . . . . . . . . . . . . . . . . .35

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Instruction Booklet
Page 2Effective: August 2010 ATC-300 2-Position Contactor
Based Transfer Switch
READ AND UNDERSTAND THE INSTRUCTIONS CONTAINED HEREIN-
AFTER BEFORE ATTEMPTING TO UNPACK, ASSEMBLE, OPERATE,
OR MAINTAIN THIS EQUIPMENT.
HAZARDOUS VOLTAGES ARE PRESENT INSIDE TRANSFER SWITCH
ENCLOSURES THAT CAN CAUSE DEATH OR SEVERE PERSONAL
INJURY. FOLLOW PROPER INSTALLATION, OPERATION, AND MAIN-
TENANCE PROCEDURES TO AVOID THESE VOLTAGES.
TRANSFER SWITCH EQUIPMENT COVERED BY THIS INSTRUCTION
BOOK IS DESIGNED AND TESTED TO OPERATE WITHIN ITS NAME-
PLATE RATINGS. OPERATION OUTSIDE OF THESE RATINGS MAY
CAUSE THE EQUIPMENT TO FAIL RESULTING IN DEATH, SERIOUS
BODILY INJURY, AND/OR PROPERTY DAMAGE. ALL RESPONSIBLE
PERSONNEL SHOULD LOCATE THE DOOR MOUNTED EQUIPMENT
NAMEPLATE AND BE FAMILIAR WITH THE INFORMATION PROVIDED
ON THE NAMEPLATE. A TYPICAL EQUIPMENT NAMEPLATE IS
SHOWN IN FIGURE 1.
Figure 1. Typical Automatic Transfer Switch (ATS) Equipment
Nameplate.
All possible contingencies that may arise during installation, oper-
ation, or maintenance, and all details and variations of this equip-
ment do no purport to be covered by these instructions. If further
information is desired by the purchaser regarding a particular
installation, operation, or maintenance of particular equipment,
please contact an authorized Eaton Sales Representative or the
installing contractor.
Section 1: Introduction
1.1 Preliminary Comments and Safety Precautions
This technical document is intended to cover most aspects asso-
ciated with the installation, application, operation, and mainte-
nance of the Automatic Transfer Controller (ATC-300) controlled
contactor based ATS with ratings from 40 through 400 amperes
(A). It is provided as a guide for authorized and qualified person-
nel only. Please refer to the specific WARNING and CAUTION in
Section 1.1.2 before proceeding. If further information is required
by the purchaser regarding a particular installation, application, or
maintenance activity, please contact an authorized Eaton sales
representative or the installing contractor.
1.1.1 Warranty and Liability Information
No warranties, expressed or implied, including warranties of fit-
ness for a particular purpose of merchantability, or warranties
arising from course of dealing or usage of trade, are made regard-
ing the information, recommendations and descriptions contained
herein. In no event will Eaton be responsible to the purchaser or
user in contract, in tort (including negligence), strict liability or
otherwise for any special, indirect, incidental or consequential
damage or loss whatsoever, including but not limited to damage
or loss of use of equipment, plant or power system, cost of capi-
tal, loss of power, additional expenses in the use of existing
power facilities, or claims against the purchaser or user by its
customers resulting from the use of the information and descrip-
tions contained herein.
1.1.2 Safety Precautions
All safety codes, safety standards, and/or regulations must be
strictly observed in the installation, operation, and maintenance
of this device.
THE WARNINGS AND CAUTIONS INCLUDED AS PART OF THE PRO-
CEDURAL STEPS IN THIS DOCUMENT ARE FOR PERSONAL SAFETY
AND PROTECTION OF EQUIPMENT FROM DAMAGE. AN EXAMPLE
OF A TYPICAL WARNING LABEL HEADING IS SHOWN ABOVE TO
FAMILIARIZE PERSONNEL WITH THE STYLE OF PRESENTATION.
THIS WILL HELP TO INSURE THAT PERSONNEL ARE ALERT TO
WARNINGS, WHICH APPEAR THROUGHOUT THE DOCUMENT. IN
ADDITION, WARNINGS AND CAUTIONS ARE ALL UPPER CASE AND
BOLDFACE.
COMPLETELY READ AND UNDERSTAND THE MATERIAL PRESENTED
IN THIS DOCUMENT BEFORE ATTEMPTING INSTALLATION, OPERA-
TION, OR APPLICATION OF THE EQUIPMENT. IN ADDITION, ONLY
QUALIFIED PERSONS SHOULD BE PERMITTED TO PERFORM ANY
WORK ASSOCIATED WITH THIS EQUIPMENT. ANY WIRING
INSTRUCTIONS PRESENTED IN THIS DOCUMENT MUST BE FOL-
LOWED PRECISELY. FAILURE TO DO SO COULD CAUSE PERMANENT
EQUIPMENT DAMAGE.
WARNING
Cat No: ATC3C2X20400WRU
Style No:
ASSEMBLED IN MEXICO
WITH U.S. COMPONENTS 30 - 43465
ITEM: 001
PIECE: 001
CS#: 123456
J050412234
Volts: 240
Poles: 2
Amps: 400
Phase: 1
Hertz: 60
Wire: 3
GO No: ABC0123 OF: 001
WARNING
CAUTION

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Instruction Booklet
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ATC-300 2-Postion Contactor 
Based Transfer Switch
1.2 General Information
Transfer switches are used to protect critical electrical loads
against loss of power. The load’s Source 1 power source is
backed up by a Source 2 power source. A transfer switch is
connected to both the Source 1 and Source 2 power sources and
supplies the load with power from one of the two sources. In the
event that power is lost from Source 1, the transfer switch trans-
fers the load to the Source 2 power source. This transfer is auto-
matic. Once Source 1 power is restored, the load is
automatically transferred back to the Source 1 power source
(Figure 2).
Figure 2. Typical Load Transfer Switch Schematic (Contactor
Type).
In ATS equipment, the switch’s intelligence system initiates the
transfer when the Source 1 power fails, falls below, or rises
above a preset voltage. If the Source 2 power source is a
standby generator, the ATS initiates generator startup and trans-
fers to the Source 2 power source when sufficient generator
voltage is available. When Source 1 power is restored, the ATS
automatically transfers back and initiates generator shutdown.
In the event the Source 1 power source fails and the Source 2
power source does not appear, the ATS remains connected to
the Source 1 power source until the Source 2 power source does
appear. Conversely, if connected to the Source 2 power source
and the Source 2 power source fails while the Source 1 power
source is still unavailable, the ATS remains connected to the
Source 2 power source.
ATSs automatically perform the transfer function and include
three basic elements:
1. A power contactor to connect and disconnect the load to
and from either power source.
2. Solenoids to make the transfer of the main contacts from
source to source.
3. Intelligence/supervisory circuits to constantly monitor the
condition of the power sources and thus provide the intelli-
gence necessary for the switch and related circuit operation.
1.2.1 Design Configuration
The Eaton contactor based ATS is a compact design that uses a
power contactor to transfer essential loads from one power
source to another (Figure 3 [100A]).
Figure 3. Typical Power Panel for a 100A Model.
The Eaton contactor based ATS was designed with easy installa-
tion and simplified maintenance in mind. Three main panels com-
prise the contactor based ATS design:
1. Power panel;
2. Voltage selection and transformer panel (if required); and
3. Microprocessor-based logic panel.
Source 1
Source 2
Load

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Page 4Effective: August 2010 ATC-300 2-Position Contactor
Based Transfer Switch
Figure 4. Contactor Based ATS (100A).
Each panel is independently mounted with interconnecting wiring
terminated at the connector receptacles on the ATC-300 Control-
ler. Door or individual panel removal is achieved without disturb-
ing critical connections by removing the connectors from the
receptacles and cutting the wire ties that secure the wires to the
door.
Mounting the enclosure is simple using top and bottom mounting
flanges with elongated (teardrop) mounting holes. These mount-
ing holes, along with power panel positioning bolts and pre-
tapped inserts, insure proper power panel mounting after the ini-
tial enclosure installation. Refer to Section 4 for specific mount-
ing and modification details.
Table 1. Withstand Ratings.
1.3 ATS Catalog Number Identification
Transfer switch equipment catalog numbers provide a significant
amount of relevant information that pertains to a particular piece
of equipment. The Catalog Number Identification Table (Table 2)
provides the required interpretation information. An example is
offered here to initially simplify the process.
Example: Catalog Number (circled numbers correspond to position
headings in Table 2).
The catalog number ATC3C2X20400WRU describes an ATS with
a 2 pole, 2 position Power Contactor mounted on a baseplate
within the enclosure. The intelligence represented by the logic
panel is ATC-300 controller. The continuous current rating of
this equipment is 400A and applicable at 240 Vac, 60 Hz. The
transfer switch equipment is enclosed in a NEMA 3R enclosure
and is listed for UL applications.
UL 1008 WITHSTAND AND CLOSE-ON RATINGS (kA)
UL 1008 Ampere Rating 480 Volts 600 Volts
Any
Breaker
Specific
Breaker
Any
Breaker
Specific
Breaker
100 10,000 30,000 10,000 22,000
200 10,000 30,000 22,000 35,000
260 30,000 50,000 – –
320 30,000 50,000 – –
400 30,000 50,000 – –
AT C 3 C2 X 2 0400 W R U
1to2 3 4 5 6 7 8 9to
12 13 14 15
to

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Instruction Booklet
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ATC-300 2-Postion Contactor 
Based Transfer Switch
Table 2. Transfer Switch Catalog Number Explanation
1.4 Environmental Conditions
1.4.1 Operational Conditions
Normally, an ATS is applied indoors in an electrical equipment
room. In the appropriate enclosure, it can be used for outdoor
applications where the equipment is subject to falling rain, freez-
ing temperatures, and no greater than 90% humidity (non-con-
densing). The ambient temperature range for operation is
between -20 and 70°C (-4 to 158°F).
1.5 Glossary
With respect to their use within this document and as they relate
to transfer switch and controller operation, the following termi-
nology is defined.
Available
A source is defined as “available” when it is within its undervolt-
age/overvoltage/ underfrequency/overfrequency (if applicable)
setpoint ranges for the nominal voltage and frequency setting.
Connected
Connected is defined as when the input is shorted by an external
contact or connection.
Failed or Fails
A source is defined as “failed” when it is outside of the applica-
ble voltage and frequency setpoint ranges for the nominal volt-
age and frequency setting for a time exceeding 0.5 seconds
after the time delay emergency fail (TDEF) time delays expires.
Failsafe
Failsafe is a feature that prevents disconnection from the only
available power source and also forces a transfer or re-transfer
operation to the only available power source.
Re-Transfer
Re-transfer is defined as a change of the load connection from
the Source 2 to the Source 1.
Source 1
Source 1 is the primary source (normal source, normal power
source, or normal).
Source 2
Source 2 is the secondary source (emergency source, emer-
gency power source, emergency, standby, or backup source).
Source 1: Failed or Fails
Source 1 is defined as “failed” when it is outside of its under-
voltage/overvoltage/ underfrequency/overfrequency (if applica-
ble) setpoint ranges for the nominal voltage and frequency
setting.
Source 2: Failed or Fails
Source 2 is defined as “failed” when it is outside of its under-
voltage/overvoltage/ underfrequency/overfrequency (if applica-
ble) setpoint ranges for the nominal voltage and frequency
setting for a time exceeding 0.5 seconds after the Time Delay
Emergency Fail (TDEF) time delay expires.
Transfer
Transfer is defined as a change of the load connection from the
Source 1 to the Source 2 power source.
Unconnected
Unconnected is defined as when the input is not shorted by an
external contact or connection.
POSITIONS 1 TO 2 POSITION 3 POSITION 4 POSITIONS 5 TO 6
BASIC DEVICE SWITCHING DEVICE CONTROL PANEL SWITCHING DEVICE
Automatic Transfer Switch AT Contactor CATC-300 Controller 32 Position Power Contactor C2
POSITION 7 POSITION 8 POSITIONS 9 TO 12 POSITION 13 POSITION 14 POSITION 15
SWITCHING DEVICE
ARRANGEMENT
NUMBER
OF POLES
AMPERE
RATING
VOLTAGE/
FREQUENCY ENCLOSURE LISTING
Fixed Mount X Two (2) 40A – 0040 208 Vac/60 Hz B Type 1 SUL/CSA Listing U
Three (3) 80A – 0080 220 Vac/50 Hz G Type 12 JNo Listing X
Four (4) 100A –0100 240 Vac/60 Hz WType 3R R
150A – 0150 380 Vac/50 Hz H Open K
*200A –0200 415 Vac/50 Hz O
*225A – 0225 480 Vac/60 Hz X
*260A – 0260 600 Vac/60 Hz E
*400A – 0400
*For 200A to 400A, 600 Vac application, please refer to IB01602024E

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Page 6Effective: August 2010 ATC-300 2-Position Contactor
Based Transfer Switch
Section 2: Receiving, Handling, and
Storage
2.1 Receiving
Every effort is made to ensure that the ATS equipment arrives at
its destination undamaged and ready for installation. Packing is
designed to protect internal components as well as the enclo-
sure. Care should be exercised, however, to protect the equip-
ment from impact at all times. Do not remove the protective
packaging until the equipment is ready for installation.
When the ATS equipment reaches its destination, the customer
should inspect the shipping container for any obvious signs of
rough handling and/or external damage that occurred during
transportation. Record any external and internal damage for
reporting to the transportation carrier and Eaton, once a thorough
inspection is complete. All claims should be as specific as possi-
ble and include the catalog and General Order numbers.
A shipping label affixed to the shipping container includes a vari-
ety of equipment and customer information, such as General
Order Number and catalog numbers. Make certain that this infor-
mation matches other shipping paper information.
Each transfer switch is packed securely with appropriate ship-
ping materials to prevent damage during shipment. Do not
remove or discard the packing material until the equipment is
ready for installation.
Once the top packaging is removed from the shipment, the
enclosure door can be opened. A plastic bag of documents will
be found in the enclosure, usually attached to the inside of the
enclosure. Important documents, such as test reports, wiring
diagrams, and appropriate instruction leaflets, are enclosed
within the bag and should be filed in a safe place.
2.2 Handling
As previously mentioned, ATS equipment is packaged for forklift
movement. Protect the equipment from impact at all times and
DO NOT double stack.
Once the equipment is at the installation location and ready to be
installed, packaging material can be removed and discarded.
Once the enclosure is unbolted from the wooden pallet, it can be
hand moved to its installation position. Be careful not to damage
the top or bottom enclosure mounting flanges. Refer to Section
4 of this manual for specific installation instructions.
2.3 Storage
Although well packaged, this equipment is not suitable for out-
door storage. The equipment warranty will not be applicable if
there is evidence of outdoor storage. If the equipment is to be
stored indoors for any period of time, it should be stored with its
protective packaging material in place. Protect the equipment at
all times from excessive moisture, construction dirt, corrosive
conditions, and other contaminants.
It is strongly suggested that the package-protected equipment be
stored in a climate-controlled environment with temperatures
from -30 to 85°C (-22 to 185°F) and with a relative humidity of
80% or less. DO NOT, under any circumstance, stack other
equipment on top of a transfer switch equipment enclosure,
whether packaged or not.

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Instruction Booklet
Effective: August 2010 Page 7
ATC-300 2-Postion Contactor 
Based Transfer Switch
Section 3: Equipment Description
3.1 General
The ATS consists of three basic panels:
1. The power panel;
2. The voltage selection and transformer panel (if required); and
3. The microprocessor-based logic panel.
These panels are interconnected via connector plugs and
mounted in an enclosure (Figure 5).
Figure 5. Three Basic Panels of the ATS (40-400A).
3.2 Power Panel
The power panel is used for making load, power, and neutral con-
nections. The power contactor is mounted on a steel baseplate
(Figure 6).
3.2.1 Main Contacts
This ATS incorporates a power contactor. The main contacts
connect and disconnect the load to and from the different power
sources. The power contactor is mechanically and electrically
interlocked to prevent the two sets of main contacts from being
closed simultaneously.
Figure 6. Typical Power Panel for 40-400A Models.
3.3 Voltage Selection
3.3.1 Standard Voltage Selection (208, 240, 480, 600, 
60 Hz and 220, 380, 415, 50 Hz.)
The Standard voltage selection panel consists of multi-tap trans-
formers, contained in a steel case mounted in the enclosure (Fig-
ure 7). The voltage is selected by simply removing the wires from
the default primary taps of both transformers and installing them
on the primary taps for the desired voltage. Taps are provided
for 208 to 600 Vac to satisfy application voltage. The factory
default position is 600 Vac.

POWER PANEL
LOGIC PANEL
TRANSFORMER
VOLTAGE
PANEL
SELECTION
AND
CAUTION
WHEN CHANGING THE SELECTED VOLTAGE, THE POWER MUST
BE REMOVED FROM THE ATS AND THE WIRES MUST BE MOVED
ON THE TAPS OF BOTH TRANSFORMERS.

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Based Transfer Switch
Figure 7. Standard Voltage Selection Terminals (Shown
Connected to the 480 Vac Taps).
3.4 ATC-300 Logic Panel
The ATC-300 is a microprocessor-based transfer switch logic
control package. The hardware and software of the controller
contain the intelligence/supervisory circuits that constantly moni-
tor the condition of the power sources. It provides the intelli-
gence necessary for the operation of the ATS (Figure 8).
Figure 8. ATC-300 Logic Control Panel.
The ATC-300 controller has an operating temperature of 
-20 to 70°C (-4 to 158°F).
The controller circuit board is protected by an insulating confor-
mal coating.
The specifications, under normal operating conditions, are as fol-
lows:
■Tolerance for voltage sensing function: ±1% of full scale
■Tolerance for frequency sensing function: ±0.3 Hz of setting

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ATC-300 2-Postion Contactor 
Based Transfer Switch
3.5 Features
A variety of standard and optional features are available for Eaton
ATSs. All features or combinations of features may not be avail-
able on specific ATSs. All features and/or accessories are Under-
writers Laboratories (UL) listed unless noted.
3.5.1 Standard Features
The following is a list of the standard features for the ATC-300
Controlled ATS.
1. Time Delay Normal to Emergency (TDNE)
This feature provides a time delay when transferring from
the Source 1 to the Source 2 power source. Timing begins
when Source 2 becomes available. It permits controlled
transfer of the load circuit to Source 2.
Adjustable 0 - 1800 Seconds
2. Time Delay on Engine Starting (TDES)
This feature provides a time delay of the signal to initiate
the engine/generator start cycle in order to override
momentary power outages or voltage fluctuations of
Source 1.
Adjustable 0 - 120 Seconds
3. Time Delay Emergency to Normal (TDEN)
This feature provides a time delay of the re-transfer opera-
tion to permit stabilization of Source 1. Timing begins
when Source 1 becomes available. If Source 2 fails during
timing, then re-transfer is immediate overriding the time
delay.
Adjustable 0 - 1800 Seconds
4. Time Delay for Engine Cool-down (TDEC)
This feature provides a time delay of the signal to initiate
the engine/generator stop cycle after the re-transfer opera-
tion. This allows the engine/generator to cool down by run-
ning unloaded. Timing begins on completion of the re-
transfer cycle.
Adjustable 0 - 1800 Seconds
5. Source 2 Monitoring and Protection
This feature provides monitoring and protection based on
the Source 2 voltage and/or frequency setpoints. All fea-
ture 5 functions are Failsafe operations.
5B. 1-Phase Undervoltage and Underfrequency Protection
Adjustable Undervoltage:
Dropout: 78 - 97% of nominal
Pickup: (Dropout +2%) to 99% of nominal
Adjustable Underfrequency:
Dropout: 90 - 97% of nominal
Pickup: (Dropout +1Hz) to 99% of nominal
5C. 1-Phase Overvoltage/Overfrequency
Adjustable Overvoltage:
Dropout: 105 - 110% of nominal
Pickup: 103% to (Dropout –2%) of nominal
Adjustable Overfrequency:
Dropout: 103 - 105% of nominal
Pickup:101% to (Dropout -1Hz) of nominal
5D. 1-Phase Undervoltage
Adjustable Undervoltage:
Dropout: 78 - 97% of nominal
Pickup: (Dropout +2%) to 99% of nominal
5E. 1-Phase Overvoltage
Adjustable Overvoltage:
Dropout: 105 - 110% of nominal
Pickup: 103% to (Dropout –2%) of nominal
5F. 3-Phase Undervoltage
Adjustable Undervoltage:
Dropout: 78 - 97% of nominal
Pickup: (Dropout +2%) to 99% of nominal
5G. 3-Phase Overvoltage
Adjustable Overvoltage:
Dropout: 105 - 110% of nominal
Pickup: 103% to (Dropout –2%) of nominal
5H. Phase Reversal
For a 3-phase wye source, this feature monitors the phase
sequence of the sources. If a source does not have the
same ABC or CBA sequence as the setpoint value, that
source will be considered “Unavailable.
For a 3-phase delta source, this feature should be turned off
via the PHASE REV setpoint.
5J. All Phase Undervoltage and Underfrequency Protection
Adjustable Undervoltage:
Dropout: 78 - 97% of nominal
Pickup: (Dropout +2%) to 99% of nominal
Adjustable Underfrequency:
Dropout: 90 - 97% of nominal
Pickup: (Dropout +1Hz) to 99% of nominal
5K. All Phase Overvoltage/Overfrequency
Adjustable Overvoltage:
Dropout: 105 - 110% of nominal
Pickup: 103% to (Dropout –2%) of nominal
Adjustable Overfrequency:
Dropout: 103 - 105% of nominal
Pickup: 101% to (Dropout -1Hz) of nominal

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Based Transfer Switch
5L. Source 2 3-Phase Voltage Unbalance
For a 3-phase wye source, this feature monitors phase volt-
age ratios. Voltage unbalance (%) is calculated as the dif-
ference between the maximum and minimum phase
voltage, divided by the minimum phase voltage. User-
selectable setpoints are available for dropout and pickup
unbalance settings (minimum 2% differential). Dropout is
adjustable from 5 to 20%. Pickup is adjustable from 3 to
(Dropout –2%). A setpoint for user-selectable time delay
from 10 to 30 seconds is provided. The factory default set-
points are: 5% dropout, 3% pickup, and 30 seconds time
delay. A user-selectable setpoint for enable and disable is
also provided.
When an unbalance condition is detected on Source 2, the
Unbalance Timer (TD UNBAL) starts timing. After TD
UNBAL times out, Source 2 is declared “failed”.
For a 3-phase delta source, this feature should be turned off
via the VOLT UNBAL setpoint.
6. Test Operators
Eaton ATSs are provided with a Test Pushbutton that simu-
lates a loss of the Source 1 power source as standard (Fea-
ture 6B). All programmed time delays (TDNE, TDEN, etc.)
will be performed as part of the Test. Engine run time of
the Test is equal to the Plant Exerciser (Feature 23) pro-
grammed setpoint. All Tests are Failsafe protected.
6B. Test Pushbutton
Programmable setpoints include:
1. Load or No Load Testing, or Disabled
2. Engine run time equal to the plant exerciser 
(Feature 23) setting
7. Time Delay Emergency Fail (TDEF)
This feature provides a time delay that prevents a con-
nected Source 2 power source from being declared “Failed”
in order to override momentary generator fluctuations. If
the Source 2 power source remains in the failed state then,
0.5 seconds after the TDEF timer expires, the transfer
switch will proceed with the programmed sequence for
retransfer. This time delay is only implemented when the
Source 2 power source is a generator.
Adjustable 0 - 6 Seconds
8. Time Delay Bypass Pushbutton
This feature provides a way (by pushing the Help and Step
pushbutton simultaneously) to bypass the TDNE (Feature 1)
and/or TDEN (Feature 2) time delays. The Time Delay
Bypass function, when activated by pushing the Help and
Step pushbutton simultaneously, will reduce any or all of
the programmed time delay to zero.
8C. Bypass TDEN
This feature provides one set of pushbuttons to bypass the
TDEN time delay.
8D. Bypass TDNE
This feature provides one set of pushbuttons to bypass the
TDNE time delay.
12. Power Source Annunciation
This feature provides LEDs to give switch position and
power source availability indications.
Switch Position
Provides LEDs to indicate the switch position
12C. Source 1 - Source Connected
This feature provides a green LED that, when lit, indicates
the load is connected to Source 1.
12D. Source 2 - Source Connected
This feature provides a red LED that, when lit, indicates the
load is connected to Source 2.
Power Source Availability
Provides LEDs to indicate if a power source is available.
LEDs may be integral or separate from the controller.
12G. Source 1 - Available
This feature provides a white LED that, when lit, indicates
Source 1 is available.
12H. Source 2 - Available
This feature provides an amber LED that, when lit, indi-
cates Source 2 is available.
14. Relay Auxiliary Contacts
14G. Source 1 Present: Provides two (2) normally open and two
(2) normally closed contacts. The relay is energized when
Source 1 is available.
14H. Source 2 Present: Provides two (2) normally open and two
(2) normally closed contacts. The relay is energized when
Source 2 is available.
15. Switch Position Indication Contact
This feature provides a contact that indicates if the power
switching device is in the “Open” or “Closed” position.
15E. Source 1 Position Indication Contact
This feature provides 1 dry form “C” contact that indicates
the position of the Source 1 power switching device.
15F. Source 2 Position Indication Contact
This feature provides 1 dry form “C” contact that indicates
the position of the Source 2 power switching device.
23. Plant Exerciser (PE)
This feature provides a means for automatic testing of the
engine generator set or standby power system. All pro-
grammed time delays will be performed during plant exer-
ciser operations.

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ATC-300 2-Postion Contactor 
Based Transfer Switch
23K. Plant Exerciser Selectable – Disabled/1/7/14/28 Day Inter-
val
This feature provides for automatic test operation of the
generator. Available test cycles are daily, 7, 14, or 28
days with duration equal to the programmed engine test
time.
Programmable setpoints allow for selection of three test
cycles:
■Engine Start/Run Only (No Load);
■Exercise with Load Transfer; or
■Disabled
This is a “Failsafe” operation.
26. Source 1 - Monitoring and Protection
This feature provides Source 1 monitoring and protection
functions. If the Source 1 power supply fails, then the
Automatic Transfer Controller will begin the sequence of
operations necessary to transfer the load circuit to the
Source 2 power supply. All Feature 26 monitoring and
protection functions are Failsafe operations.
26D. Go to Source 2
This feature provides the capability for an external contact
opening to initiate a load circuit transfer to the Source 2
power source. This includes starting the engine/generator,
performing the programmed time delays, and the transfer
operation. Re-transfer will occur when the external con-
tact is closed or under a Failsafe condition.
26H. Phase Reversal Protection
For a 3-phase wye source, this feature monitors the phase
sequence of the sources. If a source does not have the
same ABC or CBA sequence as the phase reversal set-
point, the source will be considered “Unavailable”.
For a 3-phase delta source, this feature should be turned
off via the PHASE REV setpoint.
26J. All Phase Undervoltage and Underfrequency Protection
Adjustable Undervoltage:
Dropout: 78 - 97% of nominal
Pickup: (Dropout +2%) to 99% of nominal
Adjustable Underfrequency:
Dropout: 90 - 97% of nominal
Pickup: (Dropout +1Hz) to 99% of nominal
26K. All Phase Overvoltage/Overfrequency
Adjustable Overvoltage:
Dropout: 105 - 110% of nominal
Pickup:103% to (Dropout –2%) of nominal
Adjustable Overfrequency:
Dropout: 103 - 105% of nominal
Pickup: 101% to (Dropout -1Hz) of nominal
26L. Source 1 3-Phase Voltage Unbalance
.For a 3-phase wye source, this feature monitors phase
voltage ratios. Voltage unbalance (%) is calculated as the
difference between the maximum and minimum phase
voltage, divided by the minimum phase voltage. User-
selectable setpoints are available for dropout and pickup
unbalance settings (minimum 2% differential). Dropout is
adjustable from 5 to 20%. Pickup is adjustable from 3 to
(Dropout –2%)). A setpoint for user-selectable time delay
from 10 to 30 seconds is provided. The factory default
setpoints are: 5% dropout, 3% pickup, and 30 seconds
time delay. A user-selectable setpoint for enable and dis-
able is also provided.
When an unbalance condition is detected on Source 1, the
Unbalance Timer (TD UNBAL) starts timing. After TD
UNBAL times out, Source 1 is declared “failed”.
For a 3-phase delta source, this feature should be turned
off via the VOLT UNBAL setpoint.
32F. In Phase Transition
Provides In-Phase transition, which is a feature that will
permit a transfer or re-transfer between 2 available
sources that have a phase angle difference of 8 degrees or
less. The In-Phase transition feature includes permissible
frequency difference and synchronization time setpoints.
In the event source 1 and source 2 fail to synchronize
within a specified amount of time, due to excessive phase
angle difference or frequency difference, then the transfer
will take place under delayed transition. Alarm relay will
energize and failure will be logged into the transfer history
as either “Sync Fail – Freq” or “Sync Fail – Phase”
depending on whether the frequency difference or the
phase difference was excessive. The adjustable frequency
difference is 0.0 to 3.0 Hz. If the synchronization does
not occur within a specified amount of time, the Alarm
relay will energize and the failure will be logged into the
Transfer History as either “Sync Fail - Freq” or “Sync Fail -
Phase” depending on whether the frequency difference or
the phase difference was excessive.
35. Pre-Transfer Signal
This feature provides a signal to a remote device prior to a
re-transfer operation. It provides one Form “C” contact
(NO/NC) for interface with other equipment (typically ele-
vator controls). The contacts close/open on a timed basis
prior to transfer in either direction. After TDNE/TDEN
times out, this relay closes and the Pre-transfer Timer
(TPRE) starts timing. After the TPRE times out, the trans-
fer proceeds by starting the TDN timer if enabled. The
pre-transfer relay opens after the transfer is complete.
Adjustable 0 - 120 Seconds
35A. Pre-Transfer Signal with 1 N.O. and 1 N.C. Contacts
This feature provides pre-transfer signal and includes 1
N.O. and 1N.C. contacts.
42. Seismic Withstand Capability
Provides transfer switch with seismic capability exceeding
the worst case Zone 4 required per both the Uniform
Building Code and the California Building Code.

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Page 12 Effective: August 2010 ATC-300 2-Position Contactor
Based Transfer Switch
3.5.2 Optional Features
The following is a list of the optional features for the ATC-300
Controlled ATS. All features or combinations of features may not
be available on specific ATSs
9B. Maintenance Selector Switch (MSS)
Marked “OFF”, “ON”. This feature provides selector
switch disconnection of control to transfer thus allowing
testing of the transfer switch control logic circuitry with-
out initiating load transfer. Positioning the MSS in the
“OFF” position isolates the control circuit, permitting man-
ual operation of the transfer switch or testing of logic cir-
cuitry without load transfer.
14. Relay Auxiliary Contacts: This feature provides form “C”
relay auxiliary contacts.
14C. Source 1 Present: Provides four (4) normally open and four
(4) normally closed contacts. The relay is energized when
Source 1 is available.
14D. Source 2 Present: Provides four (4) normally open and four
(4) normally closed contacts. The relay is energized when
Source 2 is available.
15. Switch Position Indication Contact
This feature provides a contact that indicates if the power
switching device is in the “Open” or “Closed position.
15G. Source 1 Position Indication Contact
This feature provides 3 Dry Form “C” contacts that indi-
cate the position of the Source 1 power-switching device.
15H. Source 2 Position Indication Contact
This feature provides 3 Dry Form “C” contacts that indi-
cate the position of the Source 2 power-switching device.
18. Metering
This feature includes all required external devices (CTs,
shorting blocks, fuses, etc.) for a fully functional metering
system.
18O. IQ Analyzer Normal (S1) Only
18P. IQ Analyzer Emergency (S2) Only
18Q. IQ Analyzer Normal (S1) & Emergency (S2) Switch Select-
able
18V. IQ Analyzer Load
18R. IQ DP-4000 Normal (S1) Only
18S. IQ DP-4000 Emergency (S2) Only
18T. IQ DP-4000 Normal (S1) & Emergency (S2) Switch Select-
able
18U. IQ DP-4000 Load
18AN. IQ 250/260 Normal (S1) Only
18AE. IQ 250/260 Emergency (S2) Only
18AL. IQ 250/260 Load
18W. Ammeter
A single ammeter is a true RMS sensing device that dis-
plays single phase current only.
The ammeter can be mounted on Source 1, Source 2, or
load. The meter can also be configured for 1, 2, or 3-phase
sensing by supplying one meter per phase for Source 1,
Source 2, or load. Ammeters for both Source 1 and Source
2 can also be grouped together.
23L. 24 Hour, 7day, 365 Day Programmable Plant Exerciser
This plant exerciser has two channel electronic time
switches with 365-day, 7-day, 24-hour programming. Each
channel can be independently programmed and can provide
up to 400 events. The plant exerciser offers daily, weekly
or annual programming capability with up to 99 separate
holiday periods of any duration and priority. An LCD display
indicates load status, time-of-day, weekday and date.
29G. Auto/Manual Operation
This feature provides 2-position auto/manual selector
switch marked “Auto/Manual” which permits the selection
of automatic or manual operation. Once the selector switch
is transferred to manual mode, manual transfer between
Normal (S1) and Emergency (S2) can be achieved by oper-
ating another 2-position selector switch marked “Normal-
Emergency”.
38. Stainless Steel Logic Cover
38A. Stainless Steel Cover for Device Panel
Provides an added level of security by providing a pad lock-
able stainless steel cover for use with standard transfer
switch device panel. The cover is designed for NEMA 1,
3R, 4X, and 12 applications.
38B. Stainless Steel Cover for Controller
Provides an added level of security by providing a pad lock-
able stainless steel cover for use with standard transfer
switch logic controllers and/or associated device panels.
These covers function with Eaton’s ATC series logic con-
trollers and device panels. The covers are designed for
NEMA 1, 3R, 4X, and 12 applications.
41. Space Heater With Thermostat
This feature provides a space heater and non-adjustable
thermostat. External control power is not required.
41A. Space Heater With Thermostat - 100 Watt
This feature provides a 100 watt (W) space heater with a
non-adjustable thermostat.
49B. Sensing Isolation Transformer (Up to 600 VAC only)
This feature provides 3-phase, 4-wire for Source-1 and
Source-2 sensing input on ATC controller for a high resis-
tance grounded delta system.

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Instruction Booklet
Effective: August 2010 Page 13
ATC-300 2-Postion Contactor 
Based Transfer Switch
51D1. 50kA CVX Surge Device
This feature gives protection for surge current capacity
rating 50kA, upto 480VAC by providing a low impedance
surge path to ground while supporting rated voltage. It
provides LED indication.
51F1. 100kA CVX Surge Device
This feature gives protection for surge current capacity
rating 100kA, upto 480VAC by providing a low imped-
ance surge path to ground while supporting rated volt-
age. It provides LED indication.
3.6 Enclosure
The rugged steel ATS enclosure is supplied with three door
hinges, regardless of enclosure size. They ensure proper support
of the door and door mounted devices (Figure 9). The hinges
have removable hinge pins to facilitate door removal. Certain
procedures, such as switch mounting, are simplified with the
door removed. The doors are supplied as standard with pad-lock-
able latches.
Figure 9. Typical Type 1 Enclosure (Door Closed).
The door is used to mount a variety of lights, switches, and
push-buttons, depending upon the options required for a particu-
lar ATS. All lights and switches are mounted in the plastic door-
mounted panel.
The rear of the enclosure is supplied with teardrop shaped holes
in the top and bottom mounting flanges to facilitate mounting. It
is also supplied with two positioning bolts and various pre-tapped
inserts to insure proper positioning of the power panel anytime
the power panel must be repositioned to accommodate a differ-
ent cable entry position. Cable entry holes are the responsibility
of the customer.
ATS enclosures and all internal steel mounting plates, such as
the power panel mounting plate, go through a pretreatment
cleaning system prior to painting to ensure a durable finish.
The standard ATS enclosure is NEMA 1 Type for general use.
However, a variety of enclosures are available to address almost
any environmental circumstance (see Table 3).
Table 3. Transfer Switch Equipment Enclosures
3.7 Standards
Eaton ATS equipment, enclosed in any of the enclosures listed in
Table 3, is listed for application by UL and ULC. In addition,
Eaton ATSs are listed in File E38116 by Underwriters Laborato-
ries, Inc. under Standard UL 1008. This standard covers require-
ments for automatic transfer switches intended for use in
ordinary locations to provide lighting and power as follows:
a. In emergency systems, in accordance with articles 517
and 700 in the National Electrical Code, ANSI/ NFPA 70,
and the National Fire Protection Association No. 76A;
and/or
b. In standby systems, in accordance with article 702 of the
National Electrical Code; and/or
c. In legally required standby systems in accordance with
article 701 of the National Electrical Code.
Eaton ATSs are available to meet NFPA 110 for emergency and
standby power systems, and NFPA 99 for health care facilities
when ordered with the appropriate options.
Standard UL 1008 for ATSs lists devices under the reexamina-
tion program which only require a continual physical reexamina-
tion of the components used in the product to ensure
consistency with the originally submitted device. Follow-up test-
ing is not required by UL 1008.
NEMA TYPE DESIGN PROTECTION
Open Indoor
1 Indoor Enclosed Equipment
3R Outdoor Rain, Ice Formation
12 Indoor Dust, Dirt, and
Non-Corrosive Liquids

For more information visit: www.eaton.com IB01602015E
Instruction Booklet
Page 14 Effective: August 2010 ATC-300 2-Position Contactor
Based Transfer Switch
Section 4: Installation and Wiring
4.1 General
Eaton ATSs are factory wired and tested. Installation requires
solidly mounting the enclosed unit and connecting power cables
and auxiliary pilot circuits. Physical mounting procedures and
power cable connections are covered in this section. All other
required wiring or electrical connection references are covered in
a separate Customer Wiring Booklet packaged with the ATS.
Locate the wiring schematic, review it, and keep it readily avail-
able for reference purposes during installation and testing. Once
an ATS is properly installed and wired, it should be mechanically
and electrically checked for proper installation and operation.
The procedures for these initial mechanical and electrical checks
are outlined in Section 6 of this instruction manual.
4.2 Mounting Location
Choose a location that offers a flat, rigid mounting surface capa-
ble of supporting the weight of the enclosed ATS equipment. For
standard ATSs, avoid locations that are moist, hot, or dusty.
However, Eaton offers optional enclosure designs that can be
used in special environments. If there are any doubts as to a
location’s suitability, discuss them with your Eaton representa-
tive.
Check to make certain that there are no pipes, wires, or other
mounting hazards in the immediate mounting area that could cre-
ate a problem.
Carefully remove all packing material from the ATS at the mount-
ing location. Even though an equipment inspection should have
been made when the equipment was received, make another
careful inspection of the enclosure and the enclosed ATS compo-
nents as the packing material is removed and the enclosure read-
ied for mounting. Be especially alert for distorted metal, loose
wires, or damaged components.
4.3 Mounting Procedure
All equipment enclosures and power panels are of the same
design. Only the overall physical dimensions change. Note that
the enclosure is provided with four teardrop (elongated) mounting
holes, two in the top mounting flange and two in the bottom.
Cable entry holes are not part of the enclosure when shipped
from the factory and must be provided in the field, either before
or after mounting the enclosure. Cable access may be from the
top, bottom, and/or side.
Figure 10.Typical (40A-400A) Contactor Based ATS 
Equipment (Door Open).
WARNING
BE CERTAIN THAT THE SOLID STEEL DOOR IS PROPERLY
INSTALLED BEFORE THE TRANSFER SWITCH EQUIPMENT IS PUT
INTO SERVICE. THE DOOR PROVIDES PROTECTION FROM DAN-
GEROUS VOLTAGES AT THE LINE AND LOAD TERMINALS WHEN
THE EQUIPMENT IS IN OPERATION. FAILURE TO DO SO COULD
RESULT IN PERSONAL INJURY OR DEATH.
CAUTION
SINCE THE ENCLOSED ATS MUST BE LIFTED INTO PLACE FOR
MOUNTING, BE CERTAIN THAT ADEQUATE RESOURCES ARE
AVAILABLE FOR LIFTING TO AVOID PERSONNEL INJURIES OR
EQUIPMENT DAMAGE.
CAUTION
EXTREME CARE SHOULD BE TAKEN TO PROTECT THE TRANSFER
SWITCH FROM DRILL CHIPS, FILINGS, AND OTHER CONTAMI-
NANTS WHEN MAKING THE CABLE ENTRY HOLES. EXTREME
CARE SHOULD ALSO BE TAKEN WHEN MOUNTING THE ENCLO-
SURE TO PREVENT COMPONENT DAMAGE OR A FUTURE MAL-
FUNCTION.

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Instruction Booklet
Effective: August 2010 Page 15
ATC-300 2-Postion Contactor 
Based Transfer Switch
With the enclosed ATS equipment unpacked and ready for
mounting, proceed with the following steps.
Step 1: The ATS enclosure door is hinge mounted with remov-
able hinge pins. To simplify the mounting procedure and
avoid damaging the door-mounted logic panel, it is
strongly suggested that the door be carefully removed
and put it in a safe place until mounting is complete. To
remove the door, open the door and disconnect the con-
nectors at the back of the ATC-300 logic panel.
Remove the wire ties securing the harness to the inside
of the door. Carefully remove the hinge pins then the
door from the enclosure.
Step 2: Install the required upper and lower mounting bolt
anchors and the two upper mounting bolts in the mount-
ing surface.
Step 3: Gently lift the enclosure and guide the teardrop holes in
the upper mounting flange over the upper mounting
bolts. Do not completely tighten the bolts at this time.
Step 4: While still supporting the enclosure, install the two
lower mounting bolts in the lower mounting flange.
Again, do not completely tighten the bolts at this time.
Use shims, if required, to prevent deformation of the
enclosure if the mounting surface is distorted.
Step 5: Tighten all four mounting bolts after any required shim-
ming is completed.
Figure 11.Typical Mounting of the ATS to a Mounting Surface.
Step 6: Double check to ensure that all packing and shipping
materials have been removed.
4.4 Power Cable Connections
Test all power cables prior to connection to the unit to ensure
that the conductors or cable insulation have not been damaged
while being pulled into position.
Power cables are to be connected to solderless screw type lugs
located on the ATS switching devices. Refer to the separate
Customer Wiring Booklet supplied with the ATS equipment for
power termination. Verify that the lugs supplied will accommo-
date the power cables being used. Also verify that the cables
comply with local electrical codes. Standard ATS equipment, as
supplied from the factory, will accommodate the wire sizes
shown in Table 4.
Carefully strip the insulation from the power cables to avoid nick-
ing or ringing of the conductor strands. Prepare the stripped
conductor termination end by cleaning it with a wire brush. If
aluminum conductors are used, apply an appropriate joint com-
pound to the clean conductor surface area.
Tighten the cable lugs to the torque identified on the label affixed
to the door of the unit.
ATC-300
Electrical
ase
ase
Source1
Source2
Available
Available
Connected
Connected
Load
UnitStatus
Alarm
Reset
Engine
Test Lamp
Test
Help Step
Enter
Bypass
TDNE / TDEN
WARNING
POWER CONDUCTORS MAY HAVE VOLTAGE PRESENT THAT CAN
CAUSE SEVERE PERSONAL INJURY OR DEATH. DE-ENERGIZE ALL
POWER OR CONTROL CIRCUIT CONDUCTORS TO BE CONNECTED
TO THE ATS EQUIPMENT BEFORE BEGINNING TO WORK WITH THE
CONDUCTORS AND/OR TERMINATING THEM TO THE EQUIPMENT.
CAUTION
USE OF CABLE LUGS NOT DESIGNED FOR THE ATS MAY CAUSE
HEATING PROBLEMS.
CAUTION
TO HELP PREVENT COMPONENT DAMAGE OR FUTURE MALFUNC-
TIONS, USE EXTREME CARE TO KEEP CONTAMINANTS OUT OF
THE ATS EQUIPMENT WHEN MAKING POWER CABLE CONNEC-
TIONS.
CAUTION
RUN THE POWER CABLE THROUGH THE GUTTER SPACE PROVIDED
TO THE RIGHT OR LEFT OF POWER PANEL.
WARNING
IMPROPER POWER CABLE CONNECTIONS CAN CAUSE EXCESSIVE
HEAT AND SUBSEQUENT EQUIPMENT FAILURE.

For more information visit: www.eaton.com IB01602015E
Instruction Booklet
Page 16 Effective: August 2010 ATC-300 2-Position Contactor
Based Transfer Switch
Table 4. Transfer Switch Equipment Wire Sizes
4.5 Wiring
Power sources, load conductors, and control wiring should be
connected to locations as indicated in the Customer Wiring Book-
let supplied with the ATS equipment.
Once the ATS equipment has been installed and wired, perform
the initial mechanical and electrical procedures as outlined in Sec-
tion 6 to verify that the equipment is installed and operating prop-
erly.
4.6 Engine Start Connection
The engine control contact connections are located on the logic
panel of the ATS. Connect the engine start wires to the terminals
marked 13 and 14 on J-5 connector on the ATC-300 Controller
(see Figure 12). A contact closes between these terminal when
an engine start signal is provided by the ATS logic. The wiring
diagram provides additional engine start connection information.
Use the proper wire size as listed by the generator set (Genset)
manufacturer.
TRANSFER SWITCH AMPERE RATING WIRE SIZE RANGES NUMBER OF CABLES PER PHASE TERMINAL TEMPERATURE RATING °C (°F)
100 #14-2/0 1 75 (167)
200 #6-250 KCMIL 1 75 (167)
320 #4-600 KCMIL or (2) 1/0-250 KCMIL 1 or 2 - depending on wire size used 75 (167)
400 #4-600 KCMIL or (2) 1/0-250 KCMIL 1 or 2 - depending on wire size used 75 (167)
600 #2-600 KCMIL 2 75 (167)
WARNING
POWER CONDUCTORS AND CONTROL WIRING MAY HAVE VOLT-
AGE PRESENT THAT CAN CAUSE SEVERE PERSONAL INJURY OR
DEATH. DEENERGIZE ALL POWER OR CONTROL CIRCUIT CON-
DUCTORS BEFORE BEGINNING TO PERFORM ANY WIRING ACTIV-
ITY TO OR WITHIN THE ATS EQUIPMENT.
CAUTION
ENSURE THE ATS VOLTAGE IS SET CORRECTLY. IT SHOULD BE
THE SAME AS THE SOURCE 1 AND SOURCE 2 LINE VOLTAGES.
OPERATING THE EQUIPMENT ON IMPROPER VOLTAGE CAN
CAUSE EQUIPMENT DAMAGE.
NOTICE
PRIOR TO MAKING THE ENGINE START CONNECTION TO THE
SWITCH, SET THE ENGINE GENERATOR CONTROLS SELECTOR
SWITCH IN THE OFF POSITION TO PREVENT AN UNWANTED
ENGINE START. CONTROL WIRING, SUCH AS THE ENGINE START
WIRES, MUST BE RUN IN A SEPARATE CONDUIT FROM THE
POWER CABLES.

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Instruction Booklet
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ATC-300 2-Postion Contactor 
Based Transfer Switch
Figure 12. Location of Terminals 13 and 14 on the J-5 Connector of ATC-300 Controller.
12345678910 11 12 13 14 12345678910 11 12 13 14 1234567891012345678910
J5
J7
J2
J1
J4
1
2
3
4
5
1
2
3
4
5
J3
Phase C
Phase B
Phase A
Source 1
Phase C
Phase B
Phase A
Source 1
Phase C
Phase B
Phase A
Source 2
Phase C
Phase B
Phase A
Source 2
S1 - Line
S1 - Neut
S2 - Line
Control
Power
S2 - Neut
Clk
In
Out
5V
Gnd
Programming
Port
K1 - (Com)
K1 - (NO)
K2 - (Com)
K2 - (NO)
Pretransfer - (Com)
Pretransfer - (NO)
Pretransfer - (NC)
Alarm - (Com)
Alarm - (NO)
Alarm - (NC)
Earth Ground
Gen Start - (Com)
Gen Start - (NO)
Output Relays
+32 VDC
Source 1 Closed
+32 VDC
Source 2 Closed
+32 VDC
Lockout
+32 VDC
Go To Source 2
+32 VDC
Monitor Mode
Control Inputs
8.0 in.
6.5 in.
3
4
1
2Output
Relays
J8
K4 NO
K4 C om
K3 NO
K3 Com
TERMINALS 13 & 14

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Instruction Booklet
Page 18 Effective: August 2010 ATC-300 2-Position Contactor
Based Transfer Switch
4.7 Voltage Selection Adjustments
Certain devices, such as the Voltage Selection Panel, sensing
relays, and timers, need to be set and/or calibrated prior to plac-
ing the ATS equipment in service. Adjustments for logic devices
are described in the separate instructional document dedicated to
the specific logic being used. Voltage selection adjustments are
described in this section.
4.7.1 Standard Voltage Selection Panels (208, 240, 480, 
600 V, - 60 Hz & 220, 380, 415 V, -50 Hz)
The Standard voltage selection panel consists of multi-tap trans-
formers, contained in a steel case mounted in the enclosure. To
change the voltage from the factory default 600 Vac, follow the
steps detailed below.
Step1: Loosen the six screws securing the cover of the Voltage
Selection Transformer case. Slide the cover up, then
away from the case.
Step 2: Remove the wires from the primary taps of both trans-
formers and installed them on the taps for the desired
voltage (Figure 13B). Note that only one wire per trans-
former is moved since the second wire is the zero refer-
ence.
Figure 13A. Standard Voltage Selection Panel.
Figure 13B. Standard Voltage Selection Panel.
Figure 13.
Step 3: Reinstall the cover and tighten the four screws.
CAUTION
BE SURE THAT THE CORRECT VOLTAGE IS SELECTED TO MATCH
THE SYSTEM VOLTAGE. AN IMPROPER SELECTION AND/OR CON-
NECTION COULD RESULT IN EQUIPMENT DAMAGE.
CAUTION
WHEN CHANGING THE VOLTAGE, ONE WIRE MUST BE MOVED ON
THE PRIMARY TAPS OF BOTH TRANSFORMERS.

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Instruction Booklet
Effective: August 2010 Page 19
ATC-300 2-Postion Contactor 
Based Transfer Switch
4.8 Terminal Block Wire Installation and Removal
Proceed with the following steps and associated figures to install
or remove terminal block wiring.
Step 1: Figure 14 shows two tension clamp terminal blocks.
There is a large one and small one, but the operation is
the same for both. A small tool, such as a screwdriver,
will be pushed into the square hole next to the wire hole
and a wire will be inserted into the larger circular hole on
the outer edge.
Figure 14. Tension Clamp Terminal Blocks.
Step 2: Begin by inserting a small, flathead screwdriver into the
square (tool) hole with the flat surface of the screw-
driver against the back wall of the hole. With a little bit
of force, push the screwdriver in on a slight angle
toward the center of the clamp. Be sure to slide it in
until it clicks. You will then see the clamp open in the
wire hole.
Figure 15. Screwdriver Inserted in the “Tool” Hole.
Step 3: Once the screwdriver is in place, obtain a stripped wire
(strip about 1/4 in.) and insert it into the larger circular
wire hole. Push the wire in until it can go no further.
Figure 16. Wire Inserted in the “Wire” Hole.
Step 4: While holding the wire in place, pull the screwdriver out.
The wire will now be held securely in the terminal block.
Pull on the wire to insure that it is correctly inserted into
the clamp.
Figure 17. Wire Securely Installed in the Terminal Block.
TOOL HOLE WIRE HOLE

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Page 20 Effective: August 2010 ATC-300 2-Position Contactor
Based Transfer Switch
Section 5: Operation
5.1 General
An ATS provides a power contactor to connect and disconnect
the load to and from the Source 1 and Source 2 power sources
(Section 3.2.1).
5.2 Manual Operation
To manually operate:
1. Disconnect all sources of power.
2. Disconnect the J7 connector from the ATC-300 controller.
3. Locate the manual lever on the left side of the contactor.
4. Locate the handle used to manually transfer the switch.
5. Attach the handle to the manual lever.
6. Rotate the lever down to go to Source 1.
7. Rotate the lever down again to go to Source 2.
Figure 18. ATS Manual Operating Handle in Use.
8. Once the manual operation is complete and automatic opera-
tion is desired, connect the sources of power.
9. Check for 120 Vac at J7-4 to J7-3 if Source 1 is available.
10. Check for 120 Vac at J7-2 to J7-1 if Source 2 is available.
See the Troubleshooting Guide (Table 3, Section 7 of ATC
300 Controller Instruction Booklet IB01602009E) if values
are above 130 Vac or below 110 Vac.
11. Insert the J7 connector into the controller.
12. Follow the testing procedure in Section 6 to ensure proper
automatic operation.
WARNING
DO NOT ATTEMPT TO MANUALLY OPERATE THE ATS WITH
SOURCE 1 OR SOURCE 2 AVAILABLE.
WARNING
HIGH VOLTAGES ARE PRESENT IN AND AROUND TRANSFER
SWITCH EQUIPMENT. BEFORE ATTEMPTING TO MANUALLY
TRANSFER, DISCONNECT THE LINE POWER FROM THE EQUIP-
MENT BEING SERVICED BY OPENING AND LOCKING OUT, IF POSSI-
BLE, THE NEXT HIGHEST DISCONNECT DEVICE. FAILURE TO
FOLLOW THIS PROCEDURE COULD CAUSE SEVERE PERSONAL
INJURY AND/OR DEATH.
ALWAYS TURN THE SOURCE 1 POWER OFF AND TURN THE
SOURCE 2 (IF A GENERATOR) CONTROL SELECTOR SWITCH TO
THE “OFF” POSITION BEFORE ATTEMPTING A MANUAL TRANS-
FER.